More data re solar panels and running the fridge on 12V - Page 2 - Escape Trailer Owners Community

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Old 04-18-2016, 09:03 AM   #11
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Different truck, different trailer, but at 35' I get 10A from the truck according to the monitor.
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Old 04-18-2016, 09:28 AM   #12
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Originally Posted by LeonW View Post
Doesn't it also depend upon the thickness of the wire from the alternator to the trailer? I seem to remember reading a thread about that, smacking my head, and saying 'Duh, another thing I should have done...'
According to my local Toyota dealer, when they wired our new Highlander for the 7 pin, they used the same gauge wire for power supply that Toyota does on factory wiring, 10 gauge. I believe that ETI uses that same wire size for that power wire from the 7 pin.
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Old 04-18-2016, 05:17 PM   #13
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Originally Posted by Brian B-P View Post
I think just about any vehicle capable of towing a trailer and built in the last decade or two has more than enough alternator capacity to power the refrigerator and add some charge to the battery... but the alternator doesn't run at full capacity because the correct voltage at the truck's battery is too little at the other end of the long wire to the trailer. This is highly dependent on wiring details.
...
I did a little experiment a while back. With the Escape battery switch in the "disconnect" position and the refrigerator set to 12v, all the power was being supplied by my alternator. The voltage drop from the car battery to the distribution panel at the rear of the trailer was 1.75 volts. That is a very significant drop and it means that had the Escape batteries been connected they would have been providing some power to the 'frig, rather than being charged by the car.

The moral of the story, as others have pointed out is - the wiring between the car to the 'frig is not thick enough to both run the 'frig and charge the trailer batteries. Based on a guestimated 75 foot round trip from alternator to 'frig and back to alternator, and on a 15 amp load to run the 'frig on 12 v, the wire guide at West Marine suggests that 6ga is more appropriate. Real world measurements and experiences seems to verify this.

Current solutions - solar on the trailer or simply run on propane while driving.

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Old 04-22-2016, 01:06 PM   #14
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In my trailer, I am planning on installing a DC to DC charger to resolve the 12 volt fridge operation issues. What these little devices do is convert any reasonable voltage on the input side to a nice 14.5 volts (absorption) or 13.3 volts (float) on the output side. They do this by essentially exchanging amps for volts.


So as an example, say the voltage drop from the alternator to the trailer battery would have been 1.75 volts, bringing it down from about 13.25 volts at the alternator to 11.5 volts at the trailer battery. If the trailer battery was requiring 14.5 volts to charge during the absorption phase, and the draw from the battery and the fridge was 25 amps, then a DC to DC charger would need 14.5 volts * 25 amps = 362 watts, which it can get from a 11.5 volt input source by drawing 362 watts / 11.5 volts = 31 amps.


The specific device that I plan on using is the Redarc BCDC1225-LV, which can output up to 25 amps. 25 amps is sufficient to run the 15 amp fridge AND simultaneously recharge the battery with the remaining 10 amps. Alternatively, if I'm low on battery and want to charge it up quickly, leaving the fridge on propane will allow the full 25 amps to go into the trailer battery.


There are other advantages too if you have a solar panel. The Redarc model above can replace the standard GoSolar charge controller that comes with the Escape solar package. The benefit in doing so is that the Redarc is an MPPT charge controller which is significantly more efficient at converting solar energy than a PWM solar charge controller like the GoSolar. The increase in solar collection should be in the range of 20%-40%, so the effect is like instantly upgrading your solar panels from 160 watts to the equivalent of 200-260 watts.


PWM (pulse width modulation) charge controllers are not very efficient in that they just pulse on/off the 18.5 volt input from the solar cells and then smooth the output down to 14.5 volts, so they essentially waste (18.5 - 14.5) / 18.5 = 21% of the available power. MPPT (Maximum Power Point Tracking) charge controllers on the other hand work by constantly searching to find the optimal draw from the input that will obtain the highest amount of power in terms of watts and then converting that to the 14.5 volt output during charging.


My trailer is due in 2017. Once I have all of the above installed, I'm hoping to use my vehicle as a kind of "emergency" generator. With two solar panels on the top, I don't expect to need a generator very often, if ever. In the unlikely event that do I run out of batteries, I figure that running the engine on idle for 3-5 hours won't significantly damage it compared to the countless hours that it'll be driven getting between beautiful locations. Keeping a generator and replacing unused diesel at a disposal center every year seems like a chore that I can do without given how little I plan to need non-solar power.


Ctek also sells an MPPT solar/alternator DC to DC charge controller, but I’ve heard bad things about the solar side of their unit. Supposedly, it doesn’t do a good job searching for the optimal load to apply to the solar input, so you get an inefficient power conversion.
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Old 04-22-2016, 02:11 PM   #15
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Welcome PaulK to our little world. You lost me above in your description other than it is a better controller than the stock one. What are the prices and installation procedures?
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Old 04-22-2016, 02:22 PM   #16
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Quote:
Originally Posted by paulk View Post
In my trailer, I am planning on installing a DC to DC charger to resolve the 12 volt fridge operation issues. What these little devices do is convert any reasonable voltage on the input side to a nice 14.5 volts (absorption) or 13.3 volts (float) on the output side. They do this by essentially exchanging amps for volts.
...
The specific device that I plan on using is the Redarc BCDC1225-LV, which can output up to 25 amps...
Great idea; it has been discussed here (and in the FiberglassRV forum) before...
Quote:
Originally Posted by Brian B-P View Post
If you want to get significant charging while driving, I suggest seriously looking at a DC-to-DC charger, rather than expecting the voltage that happens to result from the tug's charging system operation to be suitable. It should be no problem to pump 30 amps into the trailer's batteries with a suitable charger, but just a wire to the tug's battery won't do that.
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I think you are having trouble keeping up because of the voltage drop in the long run for the charge cable from the truck to the back of the 21. I am planning to try this DC to DC charger once I pick up my 21 next year.

ctek d205S
I'm looking forward to hearing about the results.
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Old 04-22-2016, 04:24 PM   #17
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Originally Posted by cpaharley2008 View Post
Welcome PaulK to our little world. You lost me above in your description other than it is a better controller than the stock one. What are the prices and installation procedures?
They're fairly expensive, which is why they seem to still be fairly niche.

The Ctek D250S DUAL, which I do not recommend unless you don't care too much about your solar input, is $239.97 on amazon -> Amazon.com: CTEK (56-677) D250S 5-Step, Automatic DUAL 12 Volt 20 Amp Battery Charger: Automotive

The much better Redarc BCDC1225-LV seems to not be sold in the USA, but you can import it easily. Redarc themselves will ship it to the USA, and they sell it for $659.93 Australian Dollars. I've seen it new on ebay for $390 Australian Dollars. That would make it $300 USD at today's exchange rate.

https://www.redarc.com.au/products/p...ulator-25a-lv/

Installation should be fairly easy. It needs to be close to the battery, just like other chargers, so I'm putting it under the dinette seat. It should be secured to the floor or something else solid.

For the alternator only installation, just disconnect the +12 volt wire coming from the vehicle and attach it instead to the input on the DC-DC charger. Attach the output of the DC-DC charger to whatever the +12 volt line was attached to originally. Attach the DC to DC unit's ground to ground. Done.

Installation for solar requires an additional SPDT relay to switch between the solar input and the alternator input. Attach the relay's switch controlling terminal to the +12 volt wire from the vehicle, so that it selects the vehicle's alternator input whenever the vehicle is providing power. Attach the +12 volt line to input #1 on the relay. Attach the solar cable to input #2 on the relay. Connect the common output of the relay to the DC-DC charger. Remove the GoSolar charge controller since the solar cells attach directly to the DC-DC charger. Done

The Redarc manual accessible from the link above has some visual diagrams showing various installations. I omitted a few minor details above for clarity, but those details are in the manual.

Redarc also sells a Relay that you can use, but these are commodity items and Redarc charges $100 for that component. I'd just get one from a hardware store.

In addition to the above, I'd recommend getting a Trimetric as neither the Redarc nor the Ctek has a display to show solar amps. A trimetric can show that after deducting the trailer loads, which you could argue is a better metric anyways.

So yes, in summary, DC-DC charge controllers are expensive, but still less than a $800 Honda 1000 watt generator if you are contemplating buying one for just occasional use. I should mention though that you would get a faster charge on a generator (85 amps vs 25 amps).
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Old 04-22-2016, 04:49 PM   #18
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Quote:
Originally Posted by LeonW View Post
Doesn't it also depend upon the thickness of the wire from the alternator to the trailer? I seem to remember reading a thread about that, smacking my head, and saying 'Duh, another thing I should have done...'
Escape recommended running #10 ground wire but my local installer said it wasn't possible--should have persisited. I think our fridge draws about 4 amps per hour as I was able to run the fridge on 12v during a sunny day when my 160w panel was producing that much power.
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Old 04-22-2016, 04:58 PM   #19
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I have had the Ctek D250S Dual installed in my slide-in camper for about a year now. It has been able to fully charge my 2 group 31 batteries and keep up with my 12v compressor frig and freezer while I am underway, even when my F150's alternator drops down to the 12.9v float charge.

I am hoping to get one installed in my Escape 21 sometime this year. The frig in the Escape will put a larger load on the system then what I have in my slide-in camper (about 8 amps + charge current for the battery). Also, the cable run from the 7 pin trailer connector will be longer (only about 6 ft in the slide-in), so I'm still not 100% sure this is going to work.
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Old 04-22-2016, 05:01 PM   #20
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Originally Posted by yardsale View Post
Escape recommended running #10 ground wire but my local installer said it wasn't possible--should have persisited. I think our fridge draws about 4 amps per hour as I was able to run the fridge on 12v during a sunny day when my 160w panel was producing that much power.
I had my local (expert and trusted) trailer guy run #10 wire from the engine in our SUV to the power connection at the back of the tug.

(When I finally got ahold of the right tech at Acura, they admitted that the super thin wire they use to the hitch power connection is only sufficient for trailer brake lights)

Adding the #10 wire to the tug made a HUGE improvement. We run the medium sized Casita fridge freezer when towing on 12v, not propane (don't start that debate here)

and with the "factory tow" kit from Acura (before the $100 mod) we'd arrive after 1 day of towing with 2/3 depleted Casita battery.

after the #10 wire was in, we'd arrive with a FULL Casita battery. Makes a huge difference when boondocking!!!

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